In various surgical procedures, an extracorporeal blood circuit is created to bypass the surgery site. In a cardiopulmonary surgical procedure, a bypass circuit is created where venous blood bypasses the heart and is reintroduced into an artery. Also, cardiotomy blood is scavenged from the surgical site, combined with the venous blood, and reintroduced into the patient. The extracorporeal bypass circuit performs numerous functions, including removing emboli and particulate matter entrained in the blood, regulating the carbon dioxide and oxygen content of the blood, and regulating the blood temperature.
In prior art extracorporeal bypass circuits, the venous blood is filtered and collected in a venous reservoir and the cardiotomy blood is filtered and collected in a hard shell cardiotomy reservoir. Examples of such devices include a venous reservoir as disclosed in U.S. Pat. No. 5,061,236 and a cardiotomy reservoir as disclosed in U.S. Pat. No. 4,743,371. Also, integrated venous/cardiotomy reservoirs are known, e.g., U.S. Pat. No. 4,642,089.
Some of these prior art reservoirs have blood flow paths that either cause blood stagnation or trap gas bubbles in the blood. Further, prior art cardiotomy reservoirs typically include a defoaming element that includes an antifoam agent to eliminate blood foam. Exposing blood to the antifoam agent continually is unnecessary. The present invention is directed to a combined venous and cardiotomy reservoir that provides a simpler and more efficient blood storage, filtration, and defoaming system for both venous and cardiotomy blood. Further, the present invention provides a blood reservoir that minimizes areas where blood may stagnate, and enhances the escape of gas emboli from the blood. Also, the present invention is configured so that blood defoaming filters treated with an antifoam agent are positioned above the standard operating fluid level of the reservoir so that blood foam contacts the defoaming filters and fluid blood contact with the filters is minimized.